Wetland plot located on a fen in the Rocky Mountain District of Colorado, sampled in 2020.

Summary

In 2020, the Bureau of Land Management (BLM) in partnership with Colorado Natural Heritage Program (CNHP) implemented a second pilot season testing a new Riparian and Wetland Monitoring protocol, commonly referred to as “Lentic AIM”. The Lentic AIM 2020 pilot project was carried out by a team including CNHP staff, BLM staff, and seasonal field crews. During 2020, three field crews sampled 64 sites across three western states (Colorado, Utah, and Idaho), with a bonus four sites sampled by district office staff in the Prineville District in Oregon. This document provides a way to look closely at the data collected and the metrics calculated from the data to aid in the interpretation of those data.

Plots sampled across four states during the 2020 field season.

Sample Design

The goal of the 2020 sample design was different for each of the three states sampled. For Colorado, we built on the sampling completed in 2019 to sample more sites distributed across the Northwest and Rocky Mountain Districts. These consisted of both targeted sites selected by BLM staff, as well as randomly selected sites left over from designs run for the 2019 sampling season. In Utah, only targeted sites were sampled to allow for efficient sampling while we wait for wetland mapping updates due in the coming years. In Idaho, we used a mixed sampling approach. Random designs in the Boise District were confined to allotments with upcoming permit renewals, while the design in the Idaho Falls District was run across the two field offices of interest. In addition to this random sampling, BLM staff also requested a roughly equal number of Targeted sites to be sampled during the 2020 field season.

For landscape-scale random site selection, we used the U.S. Fish and Wildlife Service’s National Wetland Inventory (NWI) to identify all vegetated wetlands on BLM land as the master sample frame. We then used a generalized random tessellation stratified (GRTS) sample design in the R statistical software ‘spsurvey’ package to select spatially-balanced, random sites from the NWI sample frame. In Colorado, points were stratified by district based on the proportion of BLM-managed wetland acreage in that district and by size to ensure the inclusion of both small and large wetlands. In Idaho, the sites were stratified by field office and size to ensure equal sampling across each of the four target field offices and the inclusion of both large and small wetlands.

The goal of random sampling was to locate and sample wetlands that may not have been identified by BLM in the past and to test the field protocol on a variety of wetland types and conditions. An additional goal was to better understand the mapping available, particularly in Idaho, where Lentic AIM sampling had never been done before. Because creating a statistically valid population estimate was a lower priority, we did not hold ourselves to strict adherence of the sample point order, which is usually important for implementing a GRTS sample design.

Lentic sites sampled in 2020 categorized by District and Field Offices
DistrictOffice	FieldOffice	ProbabilityBased	Targeted	Total
CO
Northwest District	Colorado River Valley Field Office	1	2	3
Northwest District	Kremmling Field Office	NA	2	2
Rocky Mountain District	Gunnison Field Office	2	3	5
Rocky Mountain District	Royal Gorge Field Office	2	3	5
Rocky Mountain District	San Luis Valley Field Office	3	NA	3
ID
Boise District	Bruneau Field Office	NA	3	3
Boise District	Owyhee Field Office	2	2	4
Idaho Falls District	Challis Field Office	2	5	7
Idaho Falls District	Salmon Field Office	2	5	7
OR
Prineville District	Prineville Deschutes Field Office	NA	4	4
UT
Canyon Country District	Moab Field Office	NA	6	6
Color Country District	Richfield Field Office	NA	3	3
Green River District	Price Field Office	NA	2	2
Green River District	Vernal Field Office	NA	3	3
Paria River District	Grand Staircase Escalante Nat Monument	NA	2	2
West Desert District	Fillmore Field Office	NA	3	3
West Desert District	Salt Lake Field Office	NA	6	6
Total		14	54	68

Wetland Types Sampled

In total, our field crews sampled 18 sites in Colorado, 25 in Utah, and 21 in Idaho. Additionally, four sites were sampled in Oregon by Prineville District Office Staff. The most commonly sampled wetland type in both Colorado (6) and Idaho (10) was Springs and Seeps, followed by Riparian Shrublands in Colorado (5) and Vegetated Drainageways (often called Swales) in Idaho (5). In Utah, the most common wetland type was Wet or Mesic Meadows (7), followed by Vegetated Drainageways (5) and Marshes (5).

Lentic sites sampled in 2020 categorized by General Wetland Type.
WetlandType	CO	ID	OR	UT	Total
Fen Bog	1	2	NA	2	5
Marsh	1	NA	NA	5	6
Riparian Shrubland	5	2	NA	3	10
Spring Seep	6	10	NA	3	19
Vegetated Drainageway	1	5	NA	5	11
Wet Mesic Meadow	4	2	4	7	17
Total	18	21	4	25	68

Plot Layout

The Riparian and Wetland AIM protocol allows for four different plot layout designs, depending on the shape and size of the wetland or riparian area being sampled: a spoke layout with three transects radiating from a central point, a transverse layout for long, medium-width sites between 25 and 60 m wide, a diagonal layout for long, narrow sites less than 25 m wide, and a linear layout for long, extremely narrow sites less than 2 m wide. 35 of the sites sampled in 2020 allowed for the default layout, but in Colorado and Idaho, diagonal and transverse layouts were used almost as often as the default spoke, demonstrating the need for alternative layouts.

Lentic sites sampled in 2020 categorized by plot layout.
PlotLayout	CO	ID	OR	UT	Total
Diagonal	7	NA	NA	3	10
Spoke	6	9	NA	20	35
Transverse	5	9	3	2	19
Linear	NA	3	1	NA	4
Total	18	21	4	25	68

Data Management and Analysis

Metric calculations have been completed for all sites sampled in 2020 across all methods and are now available on the BLM National AIM Sharepoint. Also available are site summaries, placing calculated metrics along side photos and descriptive information provided by the crew. Metrics provided reflect the types of information that can be calculated from AIM data, however, the Riparian and Wetland AIM Team is still working to understand what these metrics could indicate about the sites sampled. A thorough review of all data collected during the pilot phase of the Riparian and Wetland AIM program is ongoing. Until more information can be provided about the interpretation of the data, this document can be used to understand the distribution of the metrics calculated across all the sites sampled during the 2020 season. Because sample designs did not follow a statistically rigorous sampling order, these distributions cannot be used to extrapolate trends across riparian wetland areas on BLM lands, but rather to understand the range of values from this specific set of sites we sampled.

For the purposes of metric calculations, the species list used and the classifications found in that species list are based on a national list, first exported directly from USDA Plants. This means that duration, growth habit, and native/non-native status classifications were performed at a national level. Noxious designations and C-Values were determined at the state level, and included all noxious classifications based on the Administrative State. Importantly, Oregon noxious species and C-values have not yet been incorporated into the species list. Wetland Indicator Statuses were determined based on the USACE Wetland Region in which the plot was located.

Community Metrics

Community metrics are calculated based on a species list, either from Species Inventory or a list of species hit during LPI. Below explore the metrics calculated based on the full Species Inventories of sites sampled in 2020.